sql查询练习
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-- 2、查询“生物”课程比“体育”课程成绩高的所有学生的学号; select A.student_id,sw,ty from (select student_id,number as sw from score left join course on score.course_id = course.cid where course.cname = ‘生物‘) as A left join (select student_id,number as ty from score left join course on score.course_id = course.cid where course.cname = ‘物理‘) as B on A.student_id = B.student_id where sw > if(isnull(ty),0,ty); 3、查询平均成绩大于60分的同学的学号和平均成绩; select student_id,avg(number) as score_avg from score group by student_id having score_avg > 60 4.查询所有同学的学号、姓名、选课数、总成绩 select student_id, sname, course_count, score_sum from (select student_id, count(course_id) as course_count, sum(number) as score_sum from score group by student_id) as A right join student on A.student_id = student.sid 5、查询姓“李”的老师的个数; select count(1) from teacher where tname like ‘李%‘; 6、查询没学过“李平”老师课的同学的学号、姓名; select sid,sname from student where sid not in (SELECT distinct student_id from score where score.course_id in ( select cid from course left join teacher on course.teacher_id=teacher.tid where tname=‘李平‘)) -- 先查到李平老师教的所有课的ID,再取选过课的所有学生ID,再在学生表中筛选 7、查询学过“1”并且也学过编号“2”课程的同学的学号、姓名; select student_id,sname from (select student_id,course_id from score where course_id=1 or course_id=2) as B left join student on student.sid=B.student_id group by student_id having count(1)=2 8、查询学过“波多”老师所教的所有课的同学的学号、姓名; select student_id,sname from -- 1.查出学过波多老师课的同学 (select student_id,course_id from score where course_id in ( select cid from course left join teacher on course.teacher_id=teacher.tid where tname=‘波多‘) ) as B -- 3.查出所有学过波多老师课的同学 left join student on B.student_id = student.sid group by student_id HAVING count(1) = -- 2.查出波多老师所教的课程数量 (select count(1) as c from course LEFT JOIN teacher on course.teacher_id=teacher.tid group by tname having tname=‘波多‘) 9、查询课程编号“2”的成绩比课程编号“1”课程低的所有同学的学号、姓名; select * from student join (SELECT A.student_id as aid from (SELECT student_id,number from score where course_id=1) as A LEFT JOIN (SELECT student_id,number from score where course_id=2) as B on A.student_id=B.student_id where A.number > B.number) as C on aid = student.sid 查询所有的课程的名称以及对应的任课老师姓名 select cname,tname from course LEFT JOIN teacher on course.teacher_id = teacher.tid; 2、查询学生表中男女生各有多少人 select gender 性别, count(1) as 人数 from student GROUP BY gender #3、查询体育成绩等于100的学生的姓名 select sname from student where sid in (select student_id from course join score on course.cid=score.course_id where cname=‘体育‘ and number=100) 10.查询有课程成绩小于60分的同学的学号、姓名; SELECT sid, sname from student where sid IN (SELECT student_id from score where number<60) SELECT distinct student_id, sname from student join score on student.sid = score.student_id where number<60 11、查询没有学全所有课的同学的学号、姓名; 先以学生分组计数课程,与总课程比较,再在student表中取出sname SELECT sid,sname FROM student WHERE sid IN ( SELECT student_id FROM score group by student_id HAVING count(course_id) = (select count(cid) from course) ); 12查询波多老师教的课程的所有成绩记录 SELECT * from score where course_id in (select cid from course inner join teacher on course.teacher_id = teacher.tid where teacher.tname=‘波多‘); 13查询至少有一门课与学号为“001”的同学所学相同的同学的学号和姓名; select student_id,sname from student inner join score on student.sid=score.student_id where course_id in (select course_id from score where student_id=1) and student_id!=1 13、查询至少学过学号为“001”同学所有课的其他同学学号和姓名; 先查询1号学过的所有课id,再找出至少学过一课的其他人,以这些人分组得到所学课程数,与1号所学课程数对比 select student_id,sname from student inner join score on student.sid=score.student_id where course_id in (select course_id from score where student_id=1) and student_id!=1 GROUP BY student_id having count(course_id) = (select count(course_id) from score where student_id = 1) 14、查询和“002”号的同学学习的课程完全相同的其他同学学号和姓名; 个数相同 002学过的也学过 先过滤出和2号学的个数相同,且学的课2号也学过的student_id, 再按学号分组再统计学的课程个数与2号相等的同学id select student_id, sname from student inner join score on student.sid=score.student_id where (select student_id from score where student_id!=2 group by student_id having count(1) =(select count(course_id) from score where student_id=2)) and course_id in (select course_id from score where student_id = 2) GROUP BY student_id HAVING count(course_id) = (select count(1) from score where student_id = 2) 15、删除学习“苍空”老师课的score表记录; DELETE from score WHERE course_id in (SELECT cid from course INNER JOIN teacher on course.teacher_id=teacher.tid where tname=‘苍空‘) 16.向SC表中插入一些记录,这些记录要求符合以下条件: ①没有上过编号“002”课程的同学学号;②插入“002”号课程的平均成绩; 由于insert 支持 inset into tb1(xx,xx) select x1,x2 from tb2; 所有,获取所有没上过002课的所有人,获取002的平均成绩 insert into score select 0,sid,2,(select avg(number) FROM score where course_id=2) from student where sid not in (select student_id from score where course_id = 2) update score set sid=4 where sid=5 insert into score values(5,3,3,50) delete from score where sid=4 or sid=5 or sid=6 17/按平均成绩从低到高 显示所有学生的“语文”、“数学”、“英语”三门的 课程成绩,按如下形式显示: 学生ID,语文,数学,英语,有效课程数,有效平均分; select sc.student_id as 学生ID, (select number from score inner join course on score.course_id=course.cid where course.cname=‘生物‘ and score.student_id=sc.student_id) as 生物, (select number from score inner join course on score.course_id=course.cid where course.cname=‘体育‘ and score.student_id=sc.student_id) as 体育, (select number from score inner join course on score.course_id=course.cid where course.cname=‘物理‘ and score.student_id=sc.student_id) as 物理, count(sc.course_id) as 有效课程数, avg(sc.number) as 有效平均分 from score as sc group by student_id desc 18、查询各科成绩最高和最低的分:以如下形式显示:课程ID,最高分,最低分; select course_id,max(number),min(number) from score GROUP BY course_id 19、按各科平均成绩从低到高和及格率的百分数从高到低顺序; select course_id,avg(number) as avgnum, SUM(case when score.number>60 then 1 else 0 END)/count(1)*100 as percent from score group by course_id ORDER BY avgnum asc,percent desc; SELECT course_id, avg(number) as avgnum, sum(case when score.number>60 then 1 else 0 end)/count(1)*100 as percent from score group by course_id order by avgnum asc,percent desc; 20、课程平均分从高到低显示(再显示任课老师); select score.course_id,course.cname, teacher.tname,avg(if(isnull(number),0,number)) as a from course inner join score on course.cid = score.course_id inner join teacher on course.teacher_id = teacher.tid GROUP BY score.course_id order by a desc; 21、查询各科成绩前三名的记录:(不考虑成绩并列情况) 先查出第四名的成绩(分组去重),然后在成绩表中找出比第四名高的成绩的记录 select * from (select student_id, course_id, number, 1, (select number from score as s2 where s2.course_id=s1.course_id GROUP BY number ORDER BY number desc limit 3,1) as cc from score as s1) as T where T.number>T.cc; 22、查询每门课程被选修的学生数; select course_id, count(1) from score group by course_id; 23、查询出只选修了一门课程的全部学生的学号和姓名; select student_id, sname from student inner join score on student.sid = score.student_id group by student_id HAVING count(1)=1 24、查询男生、女生的人数; select * from (select count(1) as man from student where gender=‘男‘) as A, (select count(1) as feman from student where gender=‘女‘) as B 25、查询姓“张”的学生名单; select sname from student where sname like ‘张%‘ 26、查询同名同姓学生名单,并统计同名人数; SELECT sname,count(1) from student group by sname; 27、查询每门课程的平均成绩,结果按平均成绩升序排列, 平均成绩相同时,按课程号降序排列; SELECT course_id,avg(number) as a from score GROUP BY course_id ORDER BY a asc, course_id desc; 28、查询平均成绩大于85的所有学生的学号、姓名和平均成绩; select student_id,sname,avg(number) as avg from student inner join score on student.sid=score.student_id GROUP BY student_id having avg > 50; 29、查询课程名称为“数学”,且分数低于60的学生姓名和分数; SELECT student_id,score.number from student LEFT JOIN score on student.sid=score.student_id LEFT JOIN course on score.course_id=course.cid where course.cname =‘体育‘ and score.number < 60 30、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名; SELECT student_id,sname from student LEFT JOIN score on student.sid=score.student_id where course_id =3 and score.number >80 31、求选了课程的学生人数 SELECT count(distinct student_id) from score; select count(c) from ( select count(1) as c from score group by student_id) as A 32、查询选修“杨艳”老师所授课程的学生中,成绩最高的学生姓名及其成绩; select sname,number from student LEFT JOIN score on student.sid=score.student_id where score.course_id in ( SELECT cid from course INNER JOIN teacher on course.teacher_id=teacher.tid where tname=‘波多‘) ORDER BY number desc LIMIT 1; 33、查询各个课程及相应的选修人数; select course.cname,count(1) from course inner JOIN score on course.cid = score.course_id group by course_id 34、查询不同课程但成绩相同的学生的学号、课程号、学生成绩;(笛卡尔积) SELECT DISTINCT s1.sid,s2.student_id,s1.course_id,s1.number from score as s1,score as s2 where s1.number=s2.number and s1.course_id !=s2.course_id; 37查询全部学生都选的课程的课程号和课程名 select course_id,count(1) from score group by course_id having count(1) = (select count(1) from student); -- 38、查询没学过“叶平”老师讲授的任一门课程的学生姓名; select student_id,student.sname from score left join student on score.student_id = student.sid where score.course_id not in ( select cid from course left join teacher on course.teacher_id = teacher.tid where tname = ‘叶平‘ ) group by student_id -- 39、查询两门以上不及格课程的同学的学号及其平均成绩; select student_id,avg(number) from score where number < 60 group by student_id having count(1) > 2 -- 40、检索“002”课程分数小于60,按分数降序排列的同学学号; select student_id from score where course_id=2 and number<60 order by number desc -- 41、删除“002”同学的“001”课程的成绩; delete from score where course_id = 1 and student_id = 2 -- 42、查询每门课程成绩都高于57分的同学id -- 一,查出每个同学高于57分的课程数,查出每个同学所学课程数,相等 select s1.student_id from (select student_id, count(1) as c from score where number>57 group by student_id) as s1, (select student_id, count(1) as c from score group by student_id) as s2 where s1.student_id=s2.student_id and s1.c = s2.c; -- 二、查出每个同学的课程数,等于此同学大于57分的课程数, select student_id from score GROUP BY student_id HAVING count(1) = sum(case when number>57 then 1 else 0 end); -- 三、查出id不在有小于等于57分的id select student_id from score group by student_id having student_id not in (SELECT student_id from score where number<=57); -- 四、以同学分组,最小成绩都大于57的同学 select student_id from score GROUP BY student_id having min(number)>57; -- 43、查询1号课程成绩大于2号课程成绩的同学 select A.student_id from (select student_id,number from score where course_id=1) as A, (select student_id,number from score where course_id=2) as B where A.student_id = B.student_id and A.number>B.number
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求助,我刚学sql2008,现在想练习查询,苦于没有数据,要一个一个王键盘敲,时间太久,我想要几张表的代码